1. Field of the Invention
This invention relates to a method and an apparatus for decontaminating substances contaminated with radioactivity that are to be used in a nuclear power station or the like for the purpose of decontaminating such contaminated substances.
2. Description of the Prior Art
Heretofore, in a nuclear power station or the like, various parts contaminated with radioactivity are produced in the power generating equipment, the attendant equipment thereof, etc., as a result of a long-term operation.
To decontaminate such parts, a shot blasting method is generally employed. As a result, a great amount of shot blasting grit contaminated with radioactivity is produced. The amount of such contaminated grit, which is usually stored in metal drums, is enormous, so that a vast storage place is required. However, an attempt to expand the storage place will meet with objections from the inhabitants of the area, thereby causing a social problem.
It is accordingly an object of the present invention to provide a method and an apparatus for decontaminating substances contaminated with radioactivity which help to decontaminate grit contaminated with radioactivity to thereby make it possible to reduce the requisite area for storing the grit.
While in this invention the object of decontamination is mainly shot blasting grit contaminated with radioactivity, as stated above, the method and the apparatus of this invention are not restricted to the decontamination of such grit, but are also applicable to the decontamination of other substances contaminated with radioactivity.
In such a decontaminating apparatus, a problem generally experienced is the necessity to move the contaminated substance from one place to another for each decontamination process. That is, the contaminated substance is first decontaminated by using a liquid, rinsed in the same liquid, and then dried. Then, the substance is decontaminated with another liquid, rinsed in the same liquid, dried, and so on. Thus, the contaminated substance must be moved from one decontaminating apparatus to another. As a result, great space is required for installing these apparatuses. Further, it is necessary to provide a step and a device for performing the bothersome operation of moving the substance from one decontaminating apparatus to another and for mechanically and reliably grasping and releasing the substance each time it is moved.
It is an object of this invention to provide a method and an apparatus for decontaminating substances contaminated with radioactivity which require no such large space, do not necessitate any movement of the contaminated substance for each decontaminating step, and do not require any complicated apparatus for mechanically grasping and releasing the contaminated substance, whereby all of the decontamination processes can be performed in a single apparatus. In some cases, for convenience sake, a plurality of apparatuses according to the present invention may be provided, the contaminated substance being moved between these apparatuses. Such arrangement is also included in the scope of this invention for the purpose of achieving an improvement in operational efficiency, without any difference to the fact that a single apparatus can perform all the decontaminating processes.
Another object of this invention is to provide a method and an apparatus for decontaminating substances contaminated with radioactivity which make it possible to decontaminate the contaminated substances effectively and to a sufficient degree.